In order to induce the bacterial uptake of plasmids, the bacteria are made competent by treating them with

Options

A. Sodium chloride
B. Potassium chloride
C. Magnesium chloride
D. Calcium chloride

Answer

To solve the question regarding how to induce bacterial uptake of plasmids by making bacteria competent, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Competence**: Competence refers to the ability of bacteria to take up foreign DNA (like plasmids) from their environment. This process is crucial in genetic engineering and biotechnology.

2. **Identifying the Treatment**: To make bacteria competent, specific treatments are required. One common method involves using divalent cations, which help to destabilize the bacterial cell membrane and facilitate the uptake of plasmids.

3. **Recognizing Divalent Cations**: Divalent cations are ions with a +2 charge. Common examples include calcium ions (Ca²⁺) and magnesium ions (Mg²⁺). These ions interact with the negatively charged components of the bacterial cell membrane.

4. **Choosing the Right Cation**: Among the options provided:
- Sodium chloride (NaCl) contains monovalent sodium ions (Na⁺).
- Potassium chloride (KCl) contains monovalent potassium ions (K⁺).
- Magnesium chloride (MgCl₂) contains divalent magnesium ions (Mg²⁺).
- Calcium chloride (CaCl₂) contains divalent calcium ions (Ca²⁺).

5. **Conclusion**: The most effective treatment for making bacteria competent to take up plasmids is to treat them with **calcium chloride (CaCl₂)**, as it provides the necessary divalent cations that facilitate the uptake process.

### Final Answer:
To induce the bacterial uptake of plasmids, the bacteria are made competent by treating them with **calcium chloride (CaCl₂)**.

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